


Game On

by SprucePines



Category: Gravity Falls
Genre: F/M, Incest, Sibling Incest, Twincest
Language: English
Status: Completed
Published: 2016-04-08
Updated: 2016-04-08
Packaged: 2018-06-01 02:47:33
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 6,314
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6497785
Author URL: https://archiveofourown.org/users/SprucePines/pseuds/SprucePines
Summary: <blockquote class="userstuff">
              <p>After nearly getting caught by one of their parents, Dipper and Mabel decide to take a break from having sex. Things take an unusual turn. Please feel free to comment if you like.</p>
            </blockquote>





	Game On

The sound of springs resonated through Mabel’s bedroom. Each squeak was punctuated by a pair of voices alternately gasping, whimpering, moaning, or groaning. Dipper looked down at his twin sister, watching her expression twist and contort with nearly every thrust he took into her. _I wish I could burn this image into my memory forever_ , he thought.

Likewise, Mabel gazed up at her brother, watching the light peeking through the blinds glisten off his sweat-covered brow. With each thrust, she wished he could sink in deeper and deeper. _I could live the rest of my life with him inside me._

They both felt their climaxes nearing, bubbling up like a boiling pot. Dipper gradually sped up his hips while Mabel began to buck hers in sync with him. Their breathing grew thick and labored when they heard a door close down the stairs. In an instant they froze in place.

“Kids?”

It was their mother! Both twins stared at each other, a litany of curse words flying through their thoughts. Dipper looked at Mabel’s bedroom door, realizing that in their lustful zeal they had neglected to lock it.

“Dipper?” their mother’s voice called. “Mabel?”

They looked frantically at each other. “What do we do?!” Mabel hissed.

“I don’t know!” Dipper replied, keeping his voice low. “We can’t just ignore her; my car’s outside.”

Trying to steady her voice as her brother pulled his deflating member out of her, Mabel called towards the door. “I’m up here, Mom! Why are you home so early?” Dipper climbed off the bed as quietly as he could and grabbed his pants. Mabel picked up her panties and quickly pulled them on, not caring if they were inside out or not.

They heard footsteps begin to climb the staircase. “I forgot something important in my bedroom, so I excused myself from the office to come and get it. I won’t be long. Is Dipper here? His car’s still in the street.”

As Mabel made a quick adjustment to her skirt she looked to her brother, who was pulling his socks on. He gave her a shrug, his mind a blank. “He…said something about taking a walk. That was a while ago.” He flashed her a thumbs up and reached for his t-shirt.

“Everything okay in there?” their mother asked, her voice just feet from the bedroom door. “You sound out of breath.” Mabel yanked up her sweater, foregoing a bra or undershirt and jammed it over her body. She grabbed Dipper by the shoulders and roughly pushed him down to the floor on the far side of her bed just as the knob turned and the door cracked open. She plastered on a smile as their mother poked her head in.

“Hi, Princess Mom-bi!” Mabel enthused, waving a hand.

“Are you feeling sick? You look flushed.”

“Huh? Oh! No, I was just…listening to some music on my iPod and dancing around earlier.” To emphasize her point, she began rocking her torso back and forth, snapping her fingers and singing a few made up lyrics under her breath. “Cause Uptown Grunk gon’ give it to ya…Uptown Grunk gon’ give it to ya…Saturday night and we in the Shack…Just be sure you bring cash.”

Mother Pines grinned knowingly at her. “Okay, honey, but don’t overexert yourself. Not in that sweater. Maybe you should take it off.”

Mabel stiffened. “Iiiii’m more or less done with dancing, so I should be alright. But thanks, Mom.”

Mrs. Pines beamed at her daughter and ducked back into the hallway. Mabel breathed a small sigh of relief when she looked beside her leg and saw Dipper’s boxers still sitting on her bed. She snatched them up and shoved them behind her back just as their mother stuck her head back in.

“Oh. don’t forget, Mabel, your dad and I will be home late tonight. I’m just going to grab the flash drive I left behind and I’ll be on my way again.”

“Right! Okay. Thanks for that update, Mom.” With that, their mother ducked back out, closing Mabel’s door behind her. Mabel sat stock still and listened as footsteps padded down the hall and into their parents’ bedroom, paused, then came back down the hallway and down the stairs.

She heard the door open, followed by, “I’ll see you later, Mabel! And maybe give your brother a call and check on him!”

Mabel looked sideways at the edge of her bed. “I will, Mom! I’ll check on Dipper right away!”

A moment later, the front door closed. Mabel sat silent. She heard the sound of a car engine turning over, followed by the sound of said engine reversing and driving away.

She slowly counted to five in her head before letting out an expulsion of air and whirling around to look at the floor next to her bed. Dipper simply lay there, staring wide-eyed at the ceiling, one arm caught in the sleeve of his t-shirt so only the elbow protruded.

“You okay there, Dipper?”

He slowly inhaled through his nostrils. “I think so. I just…Christ, that was close!” He sat up and looked at his twin. “What if we hadn’t heard the door close? Mom might have heard us…” He trailed off.

“Doing the frickle-frackle?” she suggested.

“Not quite the wording I would have used, but yes. Or worse, she might have opened the door and caught us in the act. I mean, you and I’ve been…”

“Bumping uglies?”

“Eh…yeah…a lot lately.”

“I don’t think we’ve gone more than a day without it.”

“And we’ve already had a couple of close calls. Remember when Dad called just after we finished last week? Wondered why I was so out of breath?”

Mabel nodded, then grew concerned. “What are you saying, Dipper? That you think we should break it off?”

“No!” Dipper was quick to reply, sitting bolt upright. “Well…sort of? I’m not saying to quit altogether, but maybe you and I could stand to take a break from…”

“You bending me over backwards and shoving your cock inside me, riding me into the sunset and filling me to overflowing with your hot cum until your balls start whistling ‘O Come All Ye Faithful?’”

Dipper stared blankly at Mabel for a moment. “From _sex_ …for a while.”

Mabel thought for a moment. _He might have a point. We don’t want Mom and Dad to catch us, and we_ have _been at it like jackrabbits._ She nodded. “Okay, Dip. We can take a break.”

*********

Dipper slowly rose from his bed and stretched his arms, waking up his muscles. He and Mabel had gone three days without any sort of sexual contact. If he were being honest with himself, he was a bit surprised how well they’d done so far. To date, the only thing that happened was that one would inadvertently gaze after the other a bit too long. Dipper jumped the first time their father snapped his fingers before his face, bringing him back to earth with a proverbial thud.

“Spacing out a bit there, son?” he had asked him.

Dipper managed an embarrassed chuckle. “Must have, Dad.” If that was the worst they had to contend with during this hiatus, then things should be smooth sailing.

Neither twin was willing to admit to the other, though, that they were each beginning to feel the urge bubbling up. They each convinced themselves to tamp that down, that they needed to stick to the plan.

Dipper absent-mindedly reached up his shirt and scratched his belly as he crossed the hallway to the bathroom. As he reached for the doorknob, it seemed to magically pull away from his reach. It took him an additional fraction of a second to realize that the door was opening. He looked up to see Mabel stepping out, one bath towel wrapped around her hair in that strange turban-like configuration and another around her torso.

Dipper and Mabel both stopped and smiled at each other. “Morning, Dip,” she said, chipper as always. Dipper merely hummed his answer, vocal cords not yet woken up. He glanced down and couldn’t help but see that the edge of Mabel’s towel came to a stop just a hair below her butt, almost all of her silky smooth legs on display, and just in between them…

Dipper was shocked to find himself beginning to salivate, and he could feel his lower regions responding in kind. Mabel must have noticed something was up because she soon looked downward and her eyes widened when he saw the front of his shorts tenting outward.

He quickly threw his hands in front of himself. “Gah, sorry, Mabel. I don’t know what came over me.”

She gave him a knowing grin. “I think you do, Dipper,” she said, “but that’s okay. I get it. Bathroom’s all yours.” She stepped aside and gestured towards the open door.

Dipper passed by her, all the while telling himself, _Stick to the plan. Stick to the plan. Stick to the monkey loving plan!_

He made a point to take an extra cold shower.

*********

Later that day, Mabel found her brother in the kitchen, clattering away at his laptop keyboard. She plopped down in the chair across from him, letting out a “Whuh!” as she did so. He peered over the screen at her.

“Hey, Mabel.” He returned his attention to his work.

“So, hey, about this morning?” she asked. The clacking of the keys petered to a halt as he looked back at her.

“Yeah?” he asked slowly.

“I hope you’re not, like, mad at me or anything, are you?”

He knit his brow. “Mad at you? Why would I be mad at you?”

“Because you and I are taking this break, and I come out of the bathroom right in front of you in just a towel, and HEYOHHH! it’s suddenly a Pharrell song in your shorts.”

Dipper laughed at his sister’s reference. “No worries, Mabel. I’m not upset at you or anything.”

She grinned as she stood. “Good. Because I know you liked what you saw…and what you _didn’t_ see. Don’t want you to forget the plan, right?”

He looked blankly at her for a split-second. “Uh, yeah. Right.”

Mabel turned and skipped out of the room, humming the tune to an 80s song as she went. Dipper watched her leave, his mind already mulling over what she had said. _Did she do that…on_ purpose _? No, that can’t be right. She knows we need to stick to the plan. Right? But what she just said… Is she really on board with this, or not? Oh, man, if that_ was _on purpose, what if she’s planning on something more?_

He set his jaw. _Well, game on, sister._

*********

The next day was what the weatherman on television described as “less of a heatwave and more of a heat-tsunami.” Mabel had made a point to stay indoors as much as she possibly could. Dipper was not so lucky. A week of procrastination had caught up with him and their father had insisted that he cut the grass that day. Starting early did nothing to alleviate his suffering; even by midmorning, the temperature was approaching ninety, and expected to soar.

Mabel sat at the kitchen table, colored pencil in hand as she sketched potential sweater designs. Sure it was summer, but that was just the right time to start preparing for the upcoming colder months. As she drew she heard the drone of the lawnmower cut off, signaling that her brother had either given up in the sweltering heat or had managed to finish his chore. A few minutes later, he walked through the door, t-shirt pasted to his chest and a flop sweat coating his forehead. “Hey,” he panted as he crossed the floor to the refrigerator.

“Hot?” she asked, already knowing the answer, but curious to know Dipper’s thoughts.

“It feels like getting teabagged by the devil out there.” He opened the fridge and grabbed a bottle of Pitt Cola, pressing the cold plastic against his head. Mabel stifled a giggle as she imagined him trying to drink the soda via osmosis. The way he was caressing his forehead with it, though, sparked a tiny flutter in her stomach. It looked almost sensuous. It wasn’t hard to think back to times with the two of them in bed together, pressing up just as close, as well as closer.

With some effort, she managed to wrench her gaze away from his face only to let it land on his chest. With how his shirt was plastered to him, she could easily make out all the contours of his torso. Before she knew what was happening, his hands reached down and gripped the hem and pulled it up, revealing more of his sweaty skin.

However, he didn’t simply just yank it up and off; he did so slowly. If Mabel didn’t know any better, she might almost say deliberately. As he tugged his shirt over his head, he used it to wipe the sweat from his brow before opening the bottle and taking a big swig from it. Like the shirt, he drank slowly. She felt the fluttering intensify as she saw a small trickle of soda dribble down one side of his chin and onto his chest.

To Mabel, it was almost as if he was filming a commercial for Pitt Cola. Any second now, she half-expected him to look at a camera and hold up the bottle for the product shot. She could just picture the slogan: “Live life shirtless with Pitt.”

Dipper swallowed and pulled the bottle away with a hearty “Ahhhh!” With a brief grin and a nod, he turned and walked out of the kitchen. Mabel simply sat there for a long moment before she realized she was gripping her colored pencil hard enough that it had snapped in her hand.

 _What the ‘H?’_ she thought. _What in the name of Time Baby was that?! Was he…was he teasing me?! This whole stupid break thing was_ his _idea! Does he think this is some sort of game?_

Mabel slammed the broken pencil down on the table.

_Well two can play that game, Dipper._

*********

The heat continued for the next few days, to the point that Mabel was forced to leave off her sweaters even indoors. Instead, she had been wearing plain white tank tops, eventually ditching a bra. That night was movie night for the twins. As she went to the kitchen to prepare some popcorn and sodas, the image of shirtless Dipper drinking his soda replayed itself in her mind. The more she thought about it, the more she was convinced it was deliberate.

With a perturbed glance to the doorway leading to the living room, Mabel reached for the freezer door. She took an ice cube and, after taking one last look around to make sure she was alone, lifted up her tank top and gently rubbed the cube against her nipples. She gritted her teeth at the sudden cold, but at the same time, felt a bit of relief from the heat. Once she was satisfied that her nipples were suitably erect, she tugged her top back down and, after grabbing the snacks, returned to the living room.

Dipper sat on the couch, legs folded underneath him. She handed him a bottle of cola and set the remaining snacks on the coffee table, waiting for him to take his first drink. As he did, she stood upright, arching her back outward, just slightly. The result was the points of her breasts standing out in silhouette against the light from the television screen.

Dipper instantly coughed up the soda in his mouth, sending a bit spraying around the lip of the bottle. Mabel laughed at her twin as he coughed into one hand while simultaneously grabbing a throw pillow with the other and placing it over his crotch. “Everything alright there, Dipper?” she asked with faux innocence.

“Yeah,” he replied once he was satisfied he wasn’t going to hack up a lung. “Why wouldn’t it be?”

“You were coughing pretty bad there. Did something… _surprise_ you or something?”

“No. I just…some soda went down the wrong tube is all.”

Dipper sat sullenly as she sat down next to him, both of them knowing _exactly_ what the truth really was.

*********

“Mabel.”

Mabel looked up at her friend, Maureen, who was seated across from her in the cafeteria. “Hm?”

“Your phone just buzzed.”

She looked down to see the indicator light on her phone flashing a bright green up at her. Setting aside her fork, she picked up the phone and swiped the screen. A little number “1” hovered above the message icon. Idly, she tapped the icon and the new message before realizing a microsecond too late that it had come from Dipper.

The next thing she knew, a photo filled her screen and her eyes went wide in panic. Her brother stood, wearing only his boxer shorts. His right arm was crooked up in a flexing pose. His right hand, though, was holding his cell phone up to snap the photo, so the effect was somewhat lost. His other hand had hooked the elastic of his boxers with his thumb, pushing them downward and presenting a view of his pubic region, stopping just shy of exposing his penis.

“What is it?” Maureen asked.

Mabel quickly backed out of the messaging app and set the phone back down. “Nothing. Just click-bait. Just…very inappropriate click-bait.”

Maureen seemed to accept this explanation and returned to her lunch, allowing Mabel a chance to fume.

_What is he thinking?!_

Just then, her phone vibrated in her hand. She glanced down to see another bright green flash, indicating another text. Dubious, she swiped the screen and saw a new text from Dipper. After a moment’s hesitation, she tapped the message.

**“Sorry about that photo. I did not mean to send that to you. A bunch of the guys and I were goofing around. One of them grabbed my phone, found that photo, and thought it would be really funny to send that to you.”**

_Yeah. A likely story._

*********

Dipper cursed his alarm clock as he hopped up out of bed. _I could have sworn I set it last night!_ Apparently not, he reasoned, quickly grabbing a towel and some fresh underpants and walked into the hallway. As he passed his sister’s open doorway, he looked inside. He was greeted by Mabel’s bare bottom, bent over, giving him a full view. Her hands were at her ankles, pulling up a pair of panties. Dipper’s morning wood strained against his cotton boxers. _Dammit!_ he cursed. Her intention was not at all lost on him, even without the added bonus of seeing printed text silkscreened on her panties as she tugged them over her butt:

“U Can’t Touch This.”

Doing his best to hold in a groan, he turned and made his way to the bathroom, yet another cold shower waiting for him.

As she heard the bathroom door click closed, Mabel smirked.

“Sorry, Dipper,” she said. “But all’s fair in love and war.”

*********

 _I can’t believe you did that yesterday, Mabel,_ Dipper typed into his cell phone before hitting send. He glared across the kitchen table at her.

 _Did what, O brother dear? I have no earthly idea to what you are referring to_ , her reply said.

_You know darn well what I’m talking about, Mabes! You only adopt that tone when you know you’re guilty. “U Can’t Touch This?” Really?_

_You mean like how you ”accidentally” sent me that picture during LUNCH? Don’t think I didn’t notice you teasing me with a view of your Dippity-Doo-Dah!_

_I told you, one of the guys sent that! Although…even if I HAD been the one to send it, it was only because of you making your nipples poke out on movie night._

_I KNEW U DID THAT ON PURPOSE! AND DON’T U BLAME ME FOR THAT! THAT WAS ONLY BCUZ U MADE A BIG DEAL OF TAKING OFF UR SHIRT AND DRINKING YOUR POP! BEING ALL DIPPY FRESH!_

_Mabel you know how I feel about that name! And you were mad because of that?! What about what you said the day before? “Don’t want to forget the plan” you said. After I saw you in just a towel that morning._

_THAT WAS AN ACCIDENT, YOU BUTT!_

Both twins sat in a sullen silence, looking at each other. After a pregnant pause, Mabel tapped out a message.

_Seriously, Dipper, that was a total accident. Do you really think I haven’t taken this break seriously?_

Dipper sighed. _I’m sorry, Mabel_ , he typed. _You’re right. I should have asked you about it instead of overthinking everything. As usual._

_You do have a tendency to do that, but I didn’t behave much better after the soda thing. Do you have any idea how HAWT you looked?!_

The corner of Dipper’s mouth crooked upward. _lol_ _Really?_

_Ya rly! U’ve made it vry hard 2 not go ahead and go all Divinyls in my bedroom._

_Divinyls? What are you… Oh. OH!!!! You mean…you haven’t been…you know…either?_

Mabel rolled her eyes. _We’re texting each other, Dip. You can totally get away with using the word masturbating._

_I know! It’s just…even with all the sex, it’s weird talking about stuff like that with you._

_Mmm. I guess so… So you haven’t been…?_

_No, I haven’t been…She-Bopping (or would it be He-Bopping?) this whole time either. You gave me quite the case of blue balls yesterday morning._

Mabel giggled at Dipper’s own obscure reference. _LOL Good to know I still got it. 3:)_

Suddenly, both parents burst into the room. Both twins switched off their screens and pocketed their phones.

“Hi, kids,” Mr. Pines said, voice breathless. “Don’t bother getting up from the table. Your mother and I are going to be heading out right away this morning.”

“You are?” Dipper asked. “What’s going on?”

“I got a call from the office not five minutes ago. One of our partners in the Midwest sent us an email asking for some ‘special consultation.’” He hooked his fingers in mock quotation marks as he said that. “So I’m headed to Chicago for the weekend.”

“And I,” Mrs. Pines chimed in, “have a trip of my own this weekend. I have to drive up to Sacramento and stay up there while overseeing some server replacements. For some reason this has been on the schedule for weeks, but I only just learned about it last night in an email.”

“So we’ll both be back sometime Sunday. We’ll call you to let you know when exactly, but we want you both to stick around the house while we’re gone. No wild parties, or even low key parties, this weekend.”

The twins both chuckled at their father’s poor joke. “And we’ll leave you guys some money for food. Don’t overspend, and if you go anywhere please have your cell phones with you, okay?”

“Okay, mama,” Mabel said, while Dipper nodded. The next ten minutes were a flurry of activity as both parents dashed back and forth; checking, double-checking, even triple-checking that they had enough changes of clothing, all the toiletries they needed, that the twins would be alright for the weekend. Dipper and Mabel simply sat bewildered as their folks gathered up their things, made one last check that they weren’t forgetting anything important, and were out the door. Moments later, a pair of engines started up and drove away.

They sat staring at each other for a moment, blinking, then Dipper looked to the side to see the blinds drawn. In a heartbeat, they both shoved themselves away from the table and stood up. Mabel was moving towards her brother first, practically bowling him over as she clamped her arms around his neck and attacked his mouth with her own. Dipper caught up quickly as he steadied himself, his hands finding her hips and his mouth opening to let his sister’s tongue inside.

As they stood there kissing, she pressed her abdomen forwards, her mound grinding against him. His dick responded right away, growing thicker. Mabel released one hand from around his neck, snaking its way into his sweatpants and wrapping around him. Dipper groaned at her grip, one of his own hands slipping underneath her shirt and grasping a breast. As she squeezed him, he squeezed her in turn.

Dipper reluctantly broke the kiss and both twins gasped for air. “Bedroom?” he breathed.

Mabel grinned. “Race you,” she replied. They released each other and stomped out of the kitchen and up the stairs. They took the first open bedroom door, Dipper’s room. He shoved the door shut and made sure to lock it before returning his attention to Mabel. She had already pulled her shirt off, and took one of his hands by the wrist and placed it back on her breast. As he kneaded her, she slipped her fingers into his sweatpants and boxers and pushed them both down his legs. His cock sprung up, veins almost throbbing.

Mabel knelt down and blew a cool breath of air over him. Dipper shuddered and made a low, guttural sound. “Hmmmmm, Mabel,” he growled. She curled her fingers around him and sank her mouth down over the head. Dipper tipped his head back and shut his eyes, letting out a long sigh. “I missed this so much, Mabel.” She looked up at him and hummed her agreement. He shook from the added stimulation. “F-fuck, Mabel,” he grunted. “I won’t last long at this rate.”

She took her hand away from his cock and placed both of them on his backside. Taking a deep breath and relaxing her muscles, she pushed forward and felt the head slip into her throat. She kept taking more and more until she felt her nose press up against his navel, his pubic hair tickling her slightly. His breathing grew ragged. “Holy shit, Mabel!” She slowly pulled back until only the head was just past her lips and then sank back down. As she reached the base a second time, she swallowed, her muscles contracting around him.

Unable to hold out, Dipper gently took hold of his sister’s head as she began to pull away again. He held her still as his head exited out of her throat, just as the first spurt of cum shot out, much larger than normal. Mabel began swallowing immediately, gulping him down. His knees wobbled underneath him as he came, threatening to topple him over, so he leaned over Mabel a bit to help keep steady. As his orgasm passed, her swallowing slowed, milking the last drops before pulling off and smiling up at him.

Returning her smile, Dipper pulled Mabel to her feet and kissed her deeply, catching a few faint traces of his ejaculation on her lips. He pulled away and kissed her neck just below her earlobe, sucking gently. He moved his way down her collar to her clavicle and around to the top of her chest, slowly drooping himself down as he reached the valley between her breasts. He took one in each hand and rolled them around, squishing and squeezing them as he continued to pepper kisses in between them.

Lowering himself to his knees, Dipper relinquished his hold on her chest and much like she had done just minutes before, he took hold of her bottoms and panties and pulled them down and away, revealing her already wet sex. He kissed his way around her mound, his tongue lapping up her juices before placing a long, slow kiss directly on the top of her slip. Mabel’s fingers snagged his hair as she held him there, whimpering as she bit her bottom lip.

He slid his hand over her legs, loving their silky smoothness and carefully guiding her backwards onto his bed. Mabel let herself fall backwards onto his mattress, her hands keeping Dipper exactly where he was. Not that he would have moved away; he kept his mouth in place every step of the way, kissing and sucking at her bud. Her legs parted, and Dipper took that as an invitation. He slowly traced a finger over her slit, up and down, collecting her fluids on it before gently inserting it into her.

Mabel arched her back slightly on the bed. “Dipper,” she groaned, protracting the last syllable for as long as her breath could hold out. He soon added a second finger, and then a third, sliding them in and out of his twin effortlessly. He felt her fingers tighten their grip on his locks as she panted, “D-Dip…I’m…” He retracted his fingers and moved his mouth down over her entire sex, his tongue taking over for his digits as Mabel began to quake on the bed. Like Mabel, he swallowed down all he could get from his sister before rising to crawl atop her. Again they kissed, this time Mabel getting a taste of herself on his lips.

As they kissed, Dipper instinctively began to roll his hips, his cock prodding down against her entrance. “Dipper,” Mabel said, breaking away from him for a moment, “I can’t wait any longer.”

Dipper nodded his agreement. “Me neither.” He shifted himself slightly, just enough to get into position. Mabel reached down and spread her lips and he slipped inside. They both sighed audibly as he sank completely inside. He held himself there, giving her a series of gentle kisses on the lips, cheek, nose, and forehead. “I love you, Mabel.”

“I love you, too, Dipper,” she replied, her hands reaching down behind him and gripping the small of his back. “Let’s never take that long of a break ever again.”

He shook his head vigorously. “No. Never that long again. Or at least, not without knowing how long we need to wait.”

“Well, don’t keep me waiting any longer here, Dip,” she said, giving his rump a playful slap. With a chuckle, Dipper began to slowly roll his hips. With her recent orgasm, Mabel’s insides were well lubricated. He glided in and out, her velvety interior caressing him as he slowly thrust in his sister.

Mabel’s hands slipped down over Dipper’s buttocks. Kneading them much like he had her breasts. Her fingers snaked down the cleft, brushing over his anus. He trembled and jerked at her touch. “Mabel, what are you doing?” he asked.

“Just trying something new,” she answered. She brought a hand back around and ran a finger over his shaft as he pumped, slicking it up before returning to his backside. She rubbed the pad over his hole in a slow circle, spreading her fluid and gradually relaxing the muscles around it. She gently pressed, slowly increasing pressure until the tip popped inside.

Dipper gasped at the intrusion. “M-Mabel?” he asked, concerned. She gave him a reassuring smile, lightly kissing him before slowly pressing deeper inside. She quickly found what she was looking for, glad she decided to study up on her anatomy. She brought her fingertip up against Dipper’s prostate and began to gently rub it.

Instantly, Dipper felt an intense surge rush through him, wracking him in a violent shudder. “Holy shit!” he panted when he managed to steady himself again.

“I think Mikey likes it,” Mabel said with a grin and rubbed him again. Better prepared for it this time, he managed to keep from reacting quite as strongly, but the effect was still profound. Pins and needles pricked him all over, tingling everywhere. They both felt his organ swell up inside her, hugging her canal even closer.

Dipper was in awe. “Where did you learn about this?”

“Internet,” she answered simply. “You’re not the only one who knows how to do research.”

“You and I might have to do exchange some notes,” he said before picking up speed. Mabel matched him, rubbing the bundle of nerves with steady pressure. Dipper responded with a series of low moans and groans, his member throbbing. He felt his thrusting grow even smoother and realized that Mabel’s massage was causing him to leak more pre-ejaculate than usual. He leant down and hungrily kissed her.

Mabel returned the kiss with fervor, her free hand gripping and squeezing one of Dipper’s buttocks. His flared head, aided by their combined lubrication, brushed and tickled her inner walls and sent several tiny jolts and shocks over her core. She increased the pressure on him just slightly, and was answered with another flare from between them.

Dipper broke the kiss with a gasp. “God, Mabel. I’m getting close again.”

She gritted her teeth as another pulse hit her. “Me, too, Dipper. Me, too.” Dipper shifted his position, lifting her hips off the bed and thrust as deeply as he could, trying almost frantically to reach as far in as possible. Mabel locked her legs around his waist and held on, feeling her next orgasm crest.

As she came, her muscles clamped around him, gripping his dick inside her as well as pulling his hips tightly against her. He ground up against her a few times before his own second orgasm struck, nearly as intense as the first. They both froze in place, minds nearly blank except for a shared intense emotion. At last, Dipper’s arms began to give out and he lowered himself onto his sister, both of them breathing heavy.

Mabel slowly ran a hand up and down his back. He answered with a gentle peck on her cheek. “Wow,” he breathed.

“Yeah,” she replied. “Wow.”

“I don’t know about you, but I could use a small breather right now.”

“Yeah. I could actually go for a drink. You want something?”

Dipper smiled as he rolled off of her. “A soda.”

“Coming right up,” she said as she climbed up. “I just need to clean up a bit.” She scampered out of the room, still nude. As she stepped out of sight, he caught a glimpse of their mingled fluids oozing down her legs. With a grin, he laid back on the bed and stared at the ceiling, looking forward to the rest of the weekend.

Mabel stepped into the kitchen and opened up the fridge, grabbing two bottles of Pitt Cola. As she closed the door, she glanced down the countertop and spied a couple of twenty dollar bills, along with a folded piece of notebook paper. She set the bottles down, stepped a bit closer and picked up the note, seeing her and Dipper’s name written in their mother’s handwriting. She flipped open the note and began to read. The more her eyes scanned over the contents, the wider her eyes became and it became a struggle not to grip the note tightly and accidentally crumple it up.

The bottles forgotten, she turned and bolted back up the stairs, crying her brother’s name as she went.

**********

“What do you think their reaction will be when they find the note you left them?” Mr. Pines asked, his cell phone to his ear.

Halfway across the country, Mrs. Pines chuckled into the mouthpiece of her own phone. “Surprise, embarrassment, mortification in Dipper’s case. How many siblings find out their parents know they’ve been having sex?”

“Not as many as those who also find out said parents aren’t mad at them for it, I’d wager,” he replied as he took a seat at his hotel room desk. “Still, even if this is the best way to avoid as much embarrassment as possible, I imagine it’s going to be extremely awkward when we get back on Sunday.”

“Let’s worry about that when Sunday comes. For now, let’s just let them process that we’ve known about them for the last couple weeks. Besides, it’s their own fault they were careless and forgot about the hidden security camera when they decided to have a make out session in the living room. After a couple days to think and talk about it between themselves, things might not be so awkward.”

“Mabel, maybe not. Dipper, though? Well, maybe Mabel will help him work through it. I think of the two of them, she’ll understand that we know they both chose this together.”

Mrs. Pines began to laugh. “Oh, you should have seen the way Mabel was acting when I came home for that flash drive.”

Mr. Pines grinned. “You mean the one you ‘forgot?’”

“They never stopped to consider I might have been in the house well before I closed the front door and called up,” she laughed. “It was actually kind of hilarious, actually, even if it did backfire a bit. I hoped the close call might make them consider coming forward with their relationship, not stop abruptly.”

“Did Dipper really leave his shorts on her bed?”

“And Mabel quickly hid them while I wasn’t looking for a second! It was like the movies we used to go see when we were dating.”

The couple laughed when Mr. Pines heard a beep from his phone. He took a look on the screen to see an incoming call.

“Uh oh,” he said. “I gotta go. Dipper’s calling me. Looks like we’re having this conversation sooner than expected.”

“Yeah,” Mrs. Pines said. “I’ve got Mabel calling me here.”

“Hopefully their minds haven’t been blown too badly. Just make sure the kids know we’re here for them. Good luck with your talk.”

“You, too, dear. Bye.” She tapped her screen to switch calls. “Hi, Pumpkin,” she said, maintaining a reassuring tone.

There was a long pause on the other end before a nervous voice replied, “Hi, Mama…I think we need to talk.”

“Yes, but actually, let me call your father and get the boys in a conference call. I think it would better if we all talked together.”


End file.
